Liquid crystal display device and method for manufacturing liquid crystal display device

Abstract

A transflective-type and a reflection-type liquid crystal display device having a high reflection efficiency and a high image quality are provided. A liquid crystal display device of the present invention is a liquid crystal display device including a reflection region, wherein the reflection region includes an insulating layer, a semiconductor layer and a reflective layer formed on a metal layer having a plurality of recesses therein; a plurality of protrusions of the metal layer, each having a bottom surface, an upper surface and a slope, are formed between the plurality of recesses of the metal layer; and a width a of a bottom surface of at least one of the plurality of protrusions in the metal layer satisfies a≦2(x+y)/tan θ, where a denotes the width of the bottom surface of each of the plurality of protrusions, x a thickness between the bottom surface and the upper surface, θ a tilt angle of the slope with respect to the bottom surface, and y a total thickness of the insulating layer, the semiconductor layer and the reflective layer.

1. A liquid crystal display device comprising a reflection region for reflecting incident light toward a display surface, wherein
 the reflection region includes a metal layer, an insulating layer formed on the metal layer, a semiconductor layer formed on the insulating layer, and a reflective layer formed on the semiconductor layer; 
 a plurality of recesses are formed in the metal layer; 
 recesses/protrusions, reflecting a shape of the metal layer, are formed in the reflective layer in the reflection region; 
 a plurality of protrusions of the metal layer, each having a bottom surface, an upper surface and a slope, are formed between the plurality of recesses of the metal layer; and 
 a width a of the bottom surface of at least one of the plurality of protrusions in the metal layer satisfies
     a≦ 2( x+y )/tan θ
 
 
 where a denotes the width of the bottom surface of each of the plurality of protrusions, x a thickness between the bottom surface and the upper surface, θ a tilt angle of the slope with respect to the bottom surface, and y a total thickness of the insulating layer, the semiconductor layer and the reflective layer. 
 
     
     
       2. The liquid crystal display device of  claim 1 , wherein the width of the bottom surface of at least one of the plurality of protrusions in the metal layer is 15.88 μm or less. 
     
     
       3. The liquid crystal display device of  claim 1 , wherein the width of the bottom surface of at least one of the plurality of protrusions in the metal layer is 1.00 μm or more. 
     
     
       4. The liquid crystal display device of  claim 1 , wherein the tilt angle of the slope of the plurality of protrusions with respect to the bottom surface is 10° or more and less than 90°. 
     
     
       5. The liquid crystal display device of  claim 1 , wherein a plurality of protruding portions of the metal layer including a stepped slope are formed between the plurality of recesses in the metal layer, wherein the stepped slope includes an upper slope, a flat portion and a lower slope, the upper surface of the protrusion is the upper surface of the protruding portion, the slope of the protrusion is the upper slope of the stepped slope, and the bottom surface of the protrusion is formed generally on the same plane as the flat portion of the stepped slope. 
     
     
       6. The liquid crystal display device of  claim 5 , wherein the lower slope of the stepped slope of the metal layer further includes a stepped slope. 
     
     
       7. The liquid crystal display device of  claim 5 , wherein a step reflecting the stepped slope of the metal layer is formed on a surface of the reflective layer. 
     
     
       8. The liquid crystal display device of  claim 7 , wherein a first recess and a second recess located inside the first recess are formed on a surface of the reflective layer. 
     
     
       9. The liquid crystal display device of  claim 5 , wherein the width of the bottom surface of at least one of the plurality of protrusions in the metal layer is 14.75 μm or less. 
     
     
       10. The liquid crystal display device of  claim 1 , wherein a tilt angle of the slope of the plurality of protrusions with respect to the bottom surface is 10° or more and 20° or less, and the width of the bottom surface of at least one of the plurality of protrusions is 2.75 μm or more and 15.88 μm or less. 
     
     
       11. The liquid crystal display device of  claim 1 , wherein the metal layer serves as one of a pair of electrodes forming a storage capacitor of the liquid crystal display device. 
     
     
       12. A method for manufacturing a liquid crystal display device having a reflection region for reflecting incident light toward a display surface, comprising:
 a step of forming a metal film on a substrate; 
 a step of shaping the metal film in the reflection region to thereby form a metal layer having a plurality of recesses; 
 a step of forming an insulating layer on the metal layer; 
 a step of forming a semiconductor layer on the insulating layer; and 
 a step of stacking a metal film on the semiconductor layer to thereby form a reflective layer having recesses/protrusions reflecting a shape of the plurality of recesses in the metal layer, wherein 
 in the step of forming a metal layer, a plurality of protrusions of the metal layer, each having a bottom surface, an upper surface and a slope, are formed between the plurality of recesses; and 
 in the step of forming a metal layer, the metal layer is formed so that a width a of the bottom surface of at least one of the plurality of protrusions satisfies
     a≦ 2( x+y )/tan θ
 
 
 where a denotes the width of the bottom surface of each of the plurality of protrusions, x a thickness between the bottom surface and the upper surface, θ a tilt angle of the slope with respect to the bottom surface, and y a total thickness of the insulating layer, the semiconductor layer and the reflective layer. 
 
     
     
       13. The manufacturing method of  claim 12 , wherein the metal layer is formed so that the width of the bottom surface of at least one of the plurality of protrusions is 15.88 μm or less. 
     
     
       14. The manufacturing method of  claim 12 , wherein the metal layer is formed so that the width of the bottom surface of at least one of the plurality of protrusions is 1.00 μm or more. 
     
     
       15. The manufacturing method of  claim 12 , wherein the metal layer is formed so that the tilt angle of the slope of the plurality of protrusions with respect to the bottom surface is 10° or more and less than 90°. 
     
     
       16. The manufacturing method of  claim 12 , wherein in the step of forming a metal layer, a plurality of protruding portions having a stepped slope and including the plurality of protrusions in upper portions thereof are formed between the plurality of recesses. 
     
     
       17. The manufacturing method of  claim 12 , wherein in the step of forming a metal layer, a protruding portion having a stepped slope with a plurality of tiers of steps and including the protrusion in an upper portion thereof is formed between the plurality of recesses. 
     
     
       18. The manufacturing method of  claim 16 , wherein in the step of forming a reflective layer, a step reflecting the stepped slope of the protruding portion of the metal layer is formed on a surface of the reflective layer. 
     
     
       19. The manufacturing method of  claim 18 , wherein in the step of forming a reflective layer, a first recess and a second recess located inside the first recess are formed on a surface of the reflective layer. 
     
     
       20. The manufacturing method of  claim 16 , wherein in the step of forming a metal layer, the metal layer is formed so that a width of the bottom portion of at least one of the plurality of protrusions in the metal layer is 14.75 μm or less. 
     
     
       21. The manufacturing method of  claim 12 , wherein in the step of forming a metal layer, the metal layer is formed so that a tilt angle of the slope of the plurality of protrusions with respect to the bottom surface is 10° or more and 20° or less, and the width of the bottom surface of at least one of the plurality of protrusions is 2.75 μm or more and 15.88 μm or less. 
     
     
       22. The manufacturing method of  claim 12 , wherein the metal layer is formed from the same metal as and concurrently with a gate electrode of a switching element of the liquid crystal display device. 
     
     
       23. A liquid crystal display device comprising a reflection region for reflecting incident light toward a display surface, wherein
 the reflection region includes a metal layer, an insulating layer formed on the metal layer, a reflective layer formed on the insulating layer; 
 a plurality of recesses are formed in the metal layer; 
 recesses/protrusions, reflecting a shape of the metal layer, are formed in the reflective layer in the reflection region; 
 a plurality of protrusions of the metal layer, each having a bottom surface, an upper surface and a slope, are formed between the plurality of recesses of the metal layer; and 
 a width a of the bottom surface of at least one of the plurality of protrusions in the metal layer satisfies
     a≦ 2( x+y )/tan θ
 
 
 where a denotes the width of the bottom surface of each of the plurality of protrusions, x a thickness between the bottom surface and the upper surface, θ a tilt angle of the slope with respect to the bottom surface, and y a total thickness of the insulating layer and the reflective layer. 
 
     
     
       24. A method for manufacturing a liquid crystal display device having a reflection region for reflecting incident light toward a display surface, comprising:
 a step of forming a metal film on a substrate; 
 a step of shaping the metal film in the reflection region to form a metal layer having a plurality of recesses; 
 a step of forming an insulating layer on the metal layer; and 
 a step of stacking a metal film on the insulating layer to thereby form a reflective layer having recesses/protrusions reflecting a shape of the plurality of recesses in the metal layer, wherein 
 in the step of forming a metal layer, a plurality of protrusions of the metal layer, each having a bottom surface, an upper surface and a slope, are formed between the plurality of recesses; and 
 in the step of forming a metal layer, the metal layer is formed so that a width a of the bottom surface of at least one of the plurality of protrusions satisfies
     a≦ 2( x+y )/tan θ
 
 
 where a denotes the width of the bottom surface of each of the plurality of protrusions, x a thickness between the bottom surface and the upper surface, θ a tilt angle of the slope with respect to the bottom surface, and y a total thickness of the insulating layer and the reflective layer.